It is known that fluids, such as lubricants, may usefully be applied to any tool during a roll forming process. This is particularly true when the forming process requires the formation of intricate shapes, slits, or bumps, on parts or when parts are being manufactured that may have a tendency to adhere to the forming tool. A primary reason for the use of lubrication during the forming process is to prolong tool life. However, several other reasons exist. For example, the presence of lubricants improves the stability and consistency of the parts being formed. This is particularly true when the parts being formed are sinusoidal in nature. Illustrative of the prior art is the disclosure of U.S. Pat. No. 4,507,948, issued to Wallis on Apr. 2, 1995.
During the roll forming process, a lubricant, generally in the form of a liquid or mist, is either wiped onto (the "wipe-on-strip" method), dripped onto (the "drip-on" method), or blown onto (the "spray-on" method) a virgin strip before or during the formation process. These methods of lubrication are also sometimes applied directly to the forming tool. These prior methods all have disadvantages because the lubricant is always applied by some type of external device in imprecise quantities with the attendant problems of waste and possible environmental harm.
The "wipe-on-strip" method is disadvantageous because it is usually applied to the virgin strip by felt, or another porous material pad. Porous materials have a fast breakdown rate and become easily clogged with dust or debris from the virgin material. Unless the pad is changed frequently, built-up contaminants on the pad can eventually be transferred into the forming tool. This combination can cause a machine wrap-up or machine shut-down. Additionally, when the wipe-on-strip method is used, there is no way of reclaiming all the lubricant as some of it soaks into the pad.
The "drip-on" method is disadvantageous because it generally results in either uneven lubrication or excessive strip lubrication. Typically, when lubricant is applied via the "drip-on" method, excess lubrication can result. While insufficient lubrication tends to cause machine wrap-ups and production loss, the drawback from excessive lubrication is lubrication waste. Even if an attempt is made to recycle the lubricant, an expensive filtering process must be employed. The utilization of a filtering process requires production down time while routine maintenance is performed on the system and thus, the loss of valuable manufacturing time.
The "spray-on" or atomizer method uses the least amount of lubricant. The lubricant is mixed with air, then sprayed on the strip or tool. The drawback to this method is that the lubricant becomes airborne when it is sprayed onto the strip or tool and is extremely difficult and expensive to reclaim. If the lubricant is sprayed onto the strip, and evaporative lubricants are used, the spray device has to be very close to the strip. If the spray device is located too far from the strip, the lubricant will evaporate while being sprayed and thus before the forming process takes place. Generally, when the spray device is used to directly lubricate the forming tool, the tool is rotating at speeds approaching 1000 RPM. In this case, the forming tool typically acts as a fan and either blows most of the lubricant away from the material and tool, or prematurely evaporates the lubricant.
Environmental issues have now become as important in the industry as the economic considerations mentioned above. Accordingly, any process that can also reduce the loss of or use of oils or lubricants and still maintain production quality would be a significant advantage. One process that addresses both of these considerations is roll forming. Current roll forming processes are also an improvement over prior systems environmentally. However, current roll forming processes still raise some environmental concerns, such as in the area of lubrication use and reclamation. By way of example, the heat exchanger industry spends millions of dollars each year on expensive roll forming lubricants which cannot be economically recycled or reclaimed. These lubricants are necessarily used in the production of every radiator, evaporator, condenser, and heater core used in every automobile. These lubricants are also used in every home air conditioner and device that is produced by roll-forming.
Accordingly, the amount and efficient distribution of fluids, such as lubricants, that are used in the forming process raise major environmental concerns for a heat exchanger manufacturer, especially during the bonding process of the heat exchanger fin to a heat exchanger tube. If extremely small traces of fluid residue remain on either component, the bonding process can become compromised. This not only reduces the effective heat exchange properties of the core, but can also cause premature failures and leaks. The manufacturer thus must wash the component before bonding to avoid these premature failures and leaks. Many washers chemically emulsify the fluids such as lubricants to remove them, thus producing environmentally unfriendly waste contaminants, the disposal of which is expensive. The evaporative type of lubricants help to alleviate this process, but they are expensive.